The present invention relates to a method and of processing waste materials, such as municipal waste or other wastes containing a relatively high percentage of fibrous material. More particularly, the invention relates to improvements in a method of recovering fibers from waste material and for conditioning the recovered fibers so that they can be used for the manufacture of shaped articles.
It is already known to comminute municipal waste or other waste materials, and to thereupon subject comminuted waste to a heating action. The heating action may include or is preceded by conversion or elimination of albumen, sugar, fats and starch from comminuted waste material. Reference may be had to U.S. Pat. Nos. 3,892,706 and 3,951,731 as well as to Swiss Pat. No. 503,576. These patents disclose comminution of waste material in hammer, impact or breaker mills to obtain a particulate material of desired granular or other size. The comminuting step is followed by segregation or destruction of the aforementioned ingredients (albumen, etc.), either prior to or in the course of the heating step.
The heating step is followed by segregation of heavier particles from lighter particles. The heating step results in conversion of comminuted waste into a granular of fibrous substance (i.e., into a granulae and/or fragments which are of wooly or felt-like consistency). Such configurations are not entirely satisfactory, especially when the recovered fibrous material is to be mixed with glue and converted into shaped articles by pressing, extrusion or by resorting to another suitable technique. The constituents of wooly or felt-like consistency are likely to affect the mechanical strength of shaped articles.